The present invention relates to a method and apparatus for treating waste gas cans by crushing. More particularly, the present invention relates to a method and apparatus capable of reliably rupturing cans containing a combustible gas or other fluid and of separating the cans and the fluid in a reduced period of time and further preventing explosive combustion of the combustible gas in the can rupturing process.
There are cans containing combustible gases (hereinafter referred to as xe2x80x9cgas cansxe2x80x9d), such as cans containing liquefied petroleum gas as a fuel for portable gas cooking stoves, gas lanterns and so forth, and cans containing liquefied petroleum gas or dimethyl ether as a propellant (aerosol cans and spray cans). If these cans are thrown away with the combustible gas remaining therein, explosive combustion often occurs in waste treating processes such as incineration and compression. It is desirable that gas cans be thrown away after all the gas contained therein has been used up. In actuality, however, there are not a few gas cans thrown away with the gas remaining therein. There are also many cases where gas cans are thrown away with the unused combustible gas filled therein because of the expiration of the time limit for use or due to other reasons.
To prevent explosive combustion of gas cans, waste treatment facilities for treating collected waste gas cans are conventionally provided with a treatment apparatus having rotating rollers with spike pins provided on the peripheral surfaces thereof or rotating rollers with rotary cutters. Gas cans are thrown into the treatment apparatus to bore the wall surfaces of the gas cans with the spike pins on the rotating rollers or to cut the gas cans with the rotary cutters, thereby releasing the gas from the cans. Thereafter, a compression process is carried out. The rotary cutters include a plurality of disk-shaped cutters, which are used to cut the gas cans into pieces of the order of several centimeters.
(Problem to be Solved by the Invention)
Most of gas cans, such as liquefied petroleum fuel gas cans, aerosol cans, and spray cans, have various diameters ranging from 35 millimeters to 110 millimeters. When various gas cans having different diameters are mixedly thrown into the conventional treatment apparatus, gas cans having a larger diameter than a set value impose an excessive load on the rotating rollers, whereas gas cans having a smaller diameter than the set value cannot satisfactorily be crushed with the rotating rollers. In the case of gas cans thrown away in an unused state and hence still containing a large amount of liquid, the gas cans may be discharged from the treatment apparatus to the outside before all the liquid is released from the gas cans in the treatment apparatus. In such a case, the residual gas and the residual liquid may flow out from the treated cans and ignite and burn. The residual liquid may contaminate the surroundings of the treatment apparatus. In a shredder type treatment apparatus adapted to cut gas cans with disk-shaped cutters, the liquid contained in the gas cans can flow out easily. However, because the can walls are cut into pieces, chips produced when the can walls are cut get mixed in the liquid flowing out of the cans, causing clogging of the solid-liquid separation filter.
An object of the present invention is to solve the above-described problems associated with the prior art and provide rotating (crushing) rollers capable of efficiently and reliably crushing and rupturing gas cans having a large amount of residual gas and liquid and of separating the gas cans and the fluid contained therein (including a combustible gas and a liquid) from each other within a reduced period of time despite the varying diameters of gas cans thrown in between the rotating rollers.
Further, when waste gas cans are thrown into the conventional waste gas can treatment apparatus, air flows into the treatment apparatus. This air may ignite and burn the combustible gas released in the treatment apparatus. Liquefied petroleum gas, e.g. propane and butane, and dimethyl ether, which are filled in fuel gas cans, aerosol cans, spray cans, etc. are combustible over a wide range of mixing ratios with respect to air. In the treatment apparatus, there is a strong possibility of the combustible gas igniting and burning because of the presence of frictional heat generated when the gas cans are bored with the spike pins and sparks produced by impact between metals. Therefore, another object of the present invention is to provide a method and apparatus for treating waste gas cans safely in a treatment apparatus having a pair of rotating rollers by preventing ignition and burning of the combustible gas in the treatment process. Other objects and advantages of the present invention will become apparent from the following description and claims and with reference to the drawings.
(Means for Solving the Problem)
The treatment apparatus according to the present invention crushes a waste gas can between a pair of rotating rollers installed in a treatment chamber and removes a residual fluid from the waste gas can. The pair of rotating rollers have two rotating shafts disposed parallel to each other and sprocket wheels disposed on each of the rotating shafts at regular spacings. The pair of rotating rollers are placed in such a manner that each sprocket wheel on one rotating shaft enters the area between a pair of adjacent sprocket wheels on the other rotating shaft. The treatment apparatus according to the present invention may have one or a plurality of the following features:
(a) The dimension by which each sprocket wheel of one rotating roller 1 enters the area between a pair of adjacent sprocket wheels of the other rotating roller 2, that is, the dimension u of radial overlap between the sprocket teeth, is
(1/4)hxe2x89xa6uxe2x89xa6(3/2)h, preferably (3/4)hxe2x89xa6uxe2x89xa6h
where h is the height of the sprocket teeth.
(b) The waste gas can has a cylindrical shape with a diameter of from 35 millimeters to 110 millimeters.
(c) The waste gas can is a can for supplying a foam substance.
(d) The waste gas can includes not only a used gas can but also an unused gas can thrown away because of the expiration of the time limit for use or due to other reasons.
(e) The treatment apparatus further includes a loading chamber for loading the waste gas can, the loading chamber being adjacent to the top of the treatment chamber, a discharge chamber for discharging the waste gas can, the discharge chamber being adjacent to the bottom of the treatment chamber, inert gas supply means capable of supplying an inert gas to the treatment chamber, and gas discharge means capable of discharging gas from the treatment chamber.
(f) The residual fluid in the waste gas can includes a residual gas and a residual liquid, and the residual gas includes liquefied petroleum gas or dimethyl ether.
(g) The atmosphere in the treatment chamber is replaced with the inert gas, whereby the oxygen concentration in the treatment chamber is maintained within a low range in which the liquefied petroleum gas or dimethyl ether will not burn explosively, and crushing of the waste gas can is carried out while the oxygen concentration in the treatment chamber is within the low range.
(h) The treatment apparatus further includes a first partitioning member for opening and closing the inlet of the loading chamber, a second partitioning member for opening and closing the passage between the loading chamber and the treatment chamber, a third partitioning member for opening and closing the passage between the treatment chamber and the discharge chamber, and a fourth partitioning member for opening and closing the outlet of the discharge chamber.
(i) The inert gas supply means is capable of supplying the inert gas to the loading chamber and the discharge chamber separately, and the gas discharge means is capable of discharging gas from the loading chamber and the discharge chamber separately.
(j) In a state where the waste gas can is received in the loading chamber and the atmosphere in the loading chamber has been replaced with the inert gas, the loading chamber and the treatment chamber are communicated with each other, and the waste gas can in the loading chamber is transferred to the treatment chamber.
(k) In a state where the atmosphere in the discharge chamber has been replaced with the inert gas, the discharge chamber and the treatment chamber are communicated with each other, and the treated gas can is transferred from the treatment chamber to the discharge chamber.
(l) The treatment apparatus includes a transfer mechanism capable of transferring the treated gas can from a lower part of the treatment chamber to an upper part of the discharge chamber.
(m) The treatment apparatus includes means for drawing a liquid discharged from the waste gas can from the treatment chamber to a liquid reservoir below the treatment chamber.
(n) The treatment apparatus includes an incinerator for incinerating the gas discharged through the gas discharge means.
The waste gas can treatment method according to the present invention crushes a waste gas can between a pair of rotating rollers installed in a treatment chamber and removes a residual fluid from the waste gas can. The treatment method according to the present invention includes the step of providing a loading chamber for loading the waste gas can, the loading chamber being adjacent to the treatment chamber, a discharge chamber for discharging the waste gas can, the discharge chamber being adjacent to the treatment chamber, inert gas supply means capable of supplying an inert gas into the loading chamber, the treatment chamber and the discharge chamber, and gas discharge means capable of discharging gas from the loading chamber, the treatment chamber and the discharge chamber; the step of operating the inert gas supply means and the gas discharge means to replace the atmosphere in each of the loading chamber, the treatment chamber and the discharge chamber with the inert gas, whereby the oxygen concentration in the treatment chamber is maintained within a low range in which the residual gas will not burn explosively; and the step of crushing the waste gas can while the oxygen concentration in the treatment chamber is within the low range. The treatment method according to the present invention may include one or a plurality of the following features singly or in combination:
(1) The residual fluid includes a residual gas and a residual liquid, and the residual gas includes liquefied petroleum gas or dimethyl ether.
(2) The inert gas includes nitrogen gas or carbon dioxide gas, and the low range in which the residual gas will not burn explosively is an oxygen concentration range of not higher than 10%.
(3) The inert gas supply means is capable of supplying the inert gas to the loading chamber and the discharge chamber separately.
(4) The gas discharge means is capable of discharging gas from the loading chamber and the discharge chamber separately.
(5) In a state where the waste gas can is received in the loading chamber and the atmosphere in the loading chamber has been replaced with the inert gas, the loading chamber and the treatment chamber are communicated with each other, and the waste gas can in the loading chamber is transferred to the treatment chamber.
(6) In a state where the atmosphere in the discharge chamber has been replaced with the inert gas, the discharge chamber and the treatment chamber are communicated with each other, and the treated gas can is transferred from the treatment chamber to the discharge chamber.
(7) The pair of rotating rollers have two rotating shafts disposed parallel to each other and sprocket wheels disposed on each of the rotating shafts at regular spacings, and the pair of rotating rollers are placed in such a manner that each sprocket wheel on one rotating shaft enters the area between a pair of adjacent sprocket wheels on the other rotating shaft.
(8) The treated gas can in the treatment chamber is transferred from a lower part of the treatment chamber to the discharge chamber through a transfer mechanism.
(9) The liquid discharged from the waste gas can in the treatment chamber is received in a liquid reservoir.
(10) The gas discharged through the gas discharge means is incinerated.